如何根据请求发送XMLHttpRequest？

var xhr = new XMLHttpRequest();

xhr.open('GET', 'http://example.com/api/data', true);

xhr.setRequestHeader('Content-Type', 'application/json');

xhr.onreadystatechange = function() {
  if (xhr.readyState === 4 && xhr.status === 200) {
    // 请求成功，处理响应数据
    var response = xhr.responseText;
    console.log(response);
  }
};

xhr.send();

var xhr = new XMLHttpRequest();
xhr.open('GET', 'http://example.com/api/data', true);
xhr.setRequestHeader('Content-Type', 'application/json');
xhr.onreadystatechange = function() {
  if (xhr.readyState === 4 && xhr.status === 200) {
    var response = xhr.responseText;
    console.log(response);
  }
};
xhr.send();